Combination running board and sidestep having a linear drive

ABSTRACT

Running board assembly for a motor vehicle having a passenger cab and a box. The running board assembly includes a linear actuator assembly partly disposed within a housing assembly, a running board operably coupled to the linear actuator assembly and movable relative to the housing assembly between a stowed position tucked underneath the vehicle, a cab entry position generally outwardly from the vehicle to support a user entering or exiting the passenger cab, and a box side step disposed generally outwardly from the vehicle and rearward of the cab entry position to provide a user with side access to the box, and a motor operably coupled to the linear actuator assembly for driving the linear actuator assembly in opposing first and second directions. The linear actuator assembly converts rotary input to linear motion to cause a drive arm having a linkage assembly to move the running board between the positions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/028,006, filed Jul. 23, 2014. The disclosure of the above applicationis incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a drive structure for use in an activerunning board system for automotive applications.

BACKGROUND OF THE INVENTION

The invention relates to a running board assembly for a motor vehicle.More particularly, the invention relates to a running board assemblyincluding a running board movable between a stowed position, a cab entryposition, and a box side step position.

SUMMARY OF THE INVENTION

According to one aspect of the invention, a running board assembly isprovided for a motor vehicle having a passenger cab and a box. Therunning board assembly includes a housing assembly, a linear actuatorassembly partly disposed within the housing assembly, a running boardoperably coupled to the linear actuator assembly and movable relative tothe housing assembly between a stowed position tucked underneath themotor vehicle, a cab entry position generally outwardly from the motorvehicle to support a user entering or exiting the passenger cab, and abox side step position disposed generally outwardly from the motorvehicle and rearward of the cab entry position to provide a user withside access to the box, and a motor operably coupled to the linearactuator assembly for driving the linear actuator assembly in opposingfirst and second directions to move the running board between the stowedposition, the cab entry position, and the box side step position. Thelinear actuator assembly converts rotary input to linear motion.

According to another aspect of the invention, a running board assemblyfor a motor vehicle having a passenger cab and a box includes a housingassembly, a linear actuator assembly partly disposed within the housingassembly, and a running board operably coupled to the linear actuatorassembly and movable relative to the housing assembly between a stowedposition tucked underneath the motor vehicle, a cab entry positiongenerally outwardly from the motor vehicle to support a user entering orexiting the passenger cab, and a box side step position disposedgenerally outwardly from the motor vehicle and rearward of the cab entryposition to provide a user with side access to the box. The runningboard assembly also includes a drive arm fixedly secured to the runningboard and operably coupled to the linear actuator assembly. The drivearm further includes at least a first and second link for moving thedrive arm as the linear actuator assembly is actuated. The running boardassembly further includes a motor operably coupled to the linearactuator assembly for driving the drive arm to pivotally move therunning board between the stowed position, the cab entry position, andthe box step side position, and an electronic control unit operablycoupled to the motor and programmed to turn off the motor after apredetermined number of armature revolutions to stop the running boardin the cab entry position.

In accordance with another embodiment, the drive arm also includes afirst stop engageable with the running board to stop the running boardin the stowed position and a second stop engageable with the runningboard to stop the running board in the box step side position.

According to yet another aspect of the invention, a running boardassembly for a motor vehicle includes a mounting bracket adapted forattachment to the motor vehicle, a running board movable relative to themounting bracket between a stowed position tucked underneath the motorvehicle, a cab entry position disposed generally outwardly from themotor vehicle, and a box side step position disposed generally outwardlyfrom the motor vehicle and generally rearward to the cab entry position,a motor operably coupled to the running board for driving movementthereof, and an electronic control unit electronically connected to themotor and programmed to turn off said motor when said running boardreaches said cab entry position. The running board assembly alsoincludes a housing assembly including a worm member operably coupled tothe motor. The housing assembly includes a zero backlash worm selflocking member, to eliminate backlash of the running board when therunning board is in the cab entry position, having a worm gear fixedlymounted on an end of a ball screw and a ball nut mounted along the ballscrew for movement relative thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of one embodiment of a running boardassembly including a running board;

FIG. 2 is a side view of a motor vehicle including the running board ina stowed position;

FIG. 3 is a side view of the motor vehicle including the running boardin a cab entry position;

FIG. 4 is a side view of the motor vehicle including the running boardin a box side step position;

FIG. 5 is a perspective view of a housing assembly with a linearactuator assembly, a drive arm, and a motor assembly of the runningboard assembly;

FIG. 6 is an exploded view of the linear actuator assembly of therunning board assembly;

FIG. 7 is a perspective view of the running board assembly including anelectronic control unit; and

FIG. 8 is a fragmentary rear perspective view of the motor vehicleincluding an end cap switch and a body-mounted switch for activatingmovement of the running board into and out of the box side stepposition.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

Referring to FIGS. 1-4 and 7 generally, a running board assembly,generally shown at 10, in one embodiment includes a running board 12, ahousing assembly 14, a drive arm 16, an idler arm 18, a linear actuatorassembly 20, a motor assembly 22, an electronic control unit 24, and atleast one mounting bracket 26. The mounting bracket 26 is adapted forattachment to a frame of a motor vehicle 28.

The running board 12 has a top wall 30 providing a tread surface 32therealong. The running board 12 is connected to the drive 16 and idler18 arms at pivots generally shown at 34. The pivots 34 are arrangedgenerally vertically in vehicle installed position and include a shaftextending through a bore in the end of the drive 16 and idler 18 armsand retained in place by a retaining ring. The idler arm 18 is mountedto a hub structure 36 which pivotally secures the idler arm 18 to a rearbracket 38. The rear bracket 38 is mounted to the mounting bracket 26which is attached to the frame of the motor vehicle 28. It isappreciated that although a single idler arm 18 is shown, the runningboard assembly 10 in another embodiment may include more than one idlerarm 18.

The drive 16 and idler 18 arms form a parallel linkage which pivotallycouples the running board 12 to a frame of the motor vehicle 28 formovement between a stowed position, as shown in FIG. 2, a cab entryposition, as shown in FIG. 3, and a box side step position, as shown inFIG. 4. In the stowed position, the running board 12 is generally tuckedunderneath the motor vehicle 28 so as to be somewhat hidden from viewand to provide a cleaner, more integrated look to the motor vehicle 28.In the cab entry position, the running board 12 extends generallyoutwardly from the motor vehicle 28 to assist users entering or exitinga passenger cab generally indicated at 40. And in the box side stepposition, the running board 12 extends generally outwardly from themotor vehicle 28 and is disposed rearward as compared to the cab entryposition in order to allow users side access to a box 41 of the motorvehicle 28. The running board 12 provides a more useful step surfacewith improved step length for box access as compared to a separate framemounted side step.

Referring to FIGS. 5 and 6, the housing assembly 14 includes a coverstructure 42 and a main housing structure 44. The cover structure 42 issecured to the main housing structure 44 by a plurality of coverfasteners 46, e.g., cover screws. The cover structure 42 and the mainhousing structure 44 define an internal chamber within the housingassembly 14. The housing assembly 14 also includes a steel tube portion48, a rear bracket 50, and a bracket 51 integrally formed with the coverstructure 42 and having an aperture for receiving a fastener 53, e.g.,nut and bolt arrangement, for securing to the rear bracket 50. Anotherbearing 67, e.g., spherical bearing with nitrile seals, is coupled tothe bracket 51. The rear bracket 50 of the housing assembly 14 issecured to the mounting bracket 26 adapted for attachment to the frameof the motor vehicle 28.

The linear actuator assembly 20 includes a ball screw member 52 disposedwithin the steel tube portion 48 and rotatable relative thereto. Theball screw member 52 is operably coupled to the motor assembly 22. Aworm member 54, e.g., plastic worm gear, is fixedly mounted toward anend of the ball screw member 52 for rotation therewith, and includes alead worm self locking member, generally shown at 55, e.g., worm gearwith self locking 4 degree lead angle. The worm member 54 can be of anysuitable configuration. A plurality of tapered roller bearings 56, e.g.,at least two, are mounted on an exterior surface of the worm member 54and/or ball screw member 52. The linear actuator assembly 20 alsoincludes an actuator shaft tube 58 with a tube insert 60 at one endoperably coupled to a spherical bearing 62, e.g., a spherical bearinghaving a PTFE liner (polytetrafluoroethylene) fitted therein and fixedlysecured to the bearing 62, preferably, spherical ball bearing havingstainless steel ball, PTFE liner and nitrile seals. At the other end ofthe actuator shaft tube 58 there is provide a bearing 64, preferably, asteel/PTFE sleeve bearing, and a ball nut 66 with internal ball returnfor linear movement thereof. Other suitable ball returns arecontemplated without departing from the scope of the invention. The ballscrew 52 and ball nut 66 have matching helical grooves. Bellows 65 areoperably fitted over at least the actuator shaft tube 58, ball nut 66,and bearing 64, operable for providing an environmental seal.

Ball screws are the method of choice in linear-actuation applications inaccordance with the present invention. Ball screws convert rotary inputto linear motion and offer several advantages over other actuators, suchas Acme screws, hydraulic or pneumatic systems, and belt, cable, orchain drives. Thus, the rotation of the ball screw 52 drives pivotalmovement of the drive arm 16. It is appreciated that other suitableactuators such as, but not limited to, air cylinder or hydrauliccylinder type, or other suitable linear motion screws are contemplatedwithout departing from the scope of the invention.

It is appreciated that in one embodiment a plurality of threads may bedefined on an exterior surface of the ball screw 52, in combination withoperational contact with the ball nut 66 internal ball returnarrangement and/or bearing 64.

Referring to FIGS. 1 and 5 generally, the drive arm 16 includes a firstend 68 rotatably coupled to the spherical bearing 62 and an opposingsecond end 70 rotatably coupled to a second mounting bracket 73 fixedlyconnected to the running board 12. The drive arm 16 includes a firstlink 72 pivotably connected to a second link 74 at a joint 75. Therotation of the ball screw 52 drives rotation of the first link 72 andpivotal movement about the joint 75 of the second link 74 to moverelative to the first link 72 causing the running board 12 to deploybetween stowed and a deployed positions. The joint 75 is mounted toanother hub structure 36 which pivotally secures the drive arm 16 to asecond rear bracket 38. This rear bracket 38 is mounted to the mountingbracket 26 which is attached to the frame of the motor vehicle 28.

Referring to FIGS. 1 and 5 through 7 generally, the motor assembly 22includes a casing structure 76 which includes a position sensing andencoding motor 78 that rotates a shaft in opposing first and seconddirections. The motor assembly 22 is secured to the linear actuatorassembly 20. More particularly, the shaft extends into the main housingstructure 44 and is fixedly secured to the worm gear 54 coupled with thelead worm self locking member 55 such that activation of the motor 78will rotate the self locking member 55 in the same direction causingrotation of the worm gear 54 which will cause rotation of the ball screwmember 52. The casing structure 76 is secured to the main housingstructure 44 by a second plurality of fasteners. It is appreciated thatthe casing structure 76 may in one embodiment be considered part of thehousing assembly 12 as the housing assembly 12 maintains the worm gearand motor components sealed from the external environment.

The electronic control unit 24 electronically controls the motorassembly 22 to effect movement of the running board 12 between thestowed, cab entry, and box side step positions. The electronic controlunit 24 is mounted within the motor vehicle 28 at a location remote fromthe housing assembly 14. The electronic control unit 24 is electricallyconnected to the motor assembly 22, to a wiring harness of the motorvehicle 28, and to a switch member 84 incorporated into a door 86 of themotor vehicle 28. In another embodiment, the electronic control unit 24may be physically mounted to the housing assembly 14 or to the motorassembly 22, and electronically connected to the motor assembly 22.

The switch member 84 in one embodiment is a door-actuated switch memberthat is part of the motor vehicle 28 and is controlled in a conventionalmanner by the door 86. The wiring harness supplies the electrical powerfrom the vehicle electrical system to the electronic control unit 24 ofthe running board assembly 10 through electrical wire members 88. Thestructure and operation of a conventional switch member which isoperationally interconnected to the vehicle door 86 is well known. It isunderstood by one skilled in the art that such switch members aretoggled by the opening or the closing of the vehicle door 86 associatedtherewith to open and close an electrical circuit. Wire members 90provide electrical connection between the electronic control unit 24 andthe motor assembly 22 so that the electronic control unit 24 can supplyelectrical power from the vehicle electrical system to the motorassembly 22 to effect the bi-directional operation thereof. Wire members92 provide electrical communication between the electronic control unit24 and the door-actuated switch member 84.

In one embodiment, the switch member 84 is a door ajar switch in a doorlatch. The motor assembly 22 is energized to move the running board 12from the stowed position to the cab entry position upon receiving asignal from the door ajar switch indicating that the vehicle door 86 hasbeen opened. The motor assembly 22 is energized to return the runningboard 12 to the stowed position upon receiving a signal from the doorajar switch indicating that the vehicle door 86 has been closed.

The running board assembly 10 has at least one stop that is internal tothe actuator and/or are external stops. It is appreciated that in oneembodiment there are no external stops.

In operation, starting with the running board 12 in the stowed position,when the vehicle door 86 is unlatched and pivoted outwardly from aclosed position to an open position, the switch member 84 associatedwith the vehicle door 86 is activated and sends a control signal to theelectronic control unit 24. The electronic control unit 24 in responseto the control signal supplies an appropriate voltage to the motorassembly 22 to cause the motor assembly 22 to begin rotational movementin a first rotational direction which will operably cause rotation ofthe ball screw member 52 to convert rotary input to linear motionthereof, thereby causing pivoting of the first link 72 relative to thesecond link 74 about joint 75 to move the running board 12 to the cabentry position. Specifically, the motor 78 rotates the lead worm 55causing rotation of the worm gear 54 in a first rotational directionwhich in turn rotates the ball screw member 52. The actuator shaft tube58 is rotatable with the ball screw member 52 and causes the drive arm16 to pivot outwardly away from the motor vehicle 28 to move the runningboard 12 to the cab entry position. The particular location of therunning board 12 in the cab entry position is electronically controlledby the motor 78. The electronic control unit 24 is programmed to stopthe motor 78 after a predetermined number of armature revolution counts.As a result, the exact location of the running board 12 in the cab entryposition may vary depending upon when the motor 78 is programmed tostop. When the electronic control unit 24 senses that the running board12 has reached the cab entry position, the electronic control unit 24turns off the motor 78.

The running board 12 is retained in the cab entry position after themotor assembly 22 is shut off as a result of at least the engagementbetween the worm gear 54 and the ball screw member 52, as it is knownthat the worm gear 54 will not be back-driven by the screw member 52.Specifically, the lead worm 55 is self locking and will not beback-driven. Thus, the lead worm 55 and/or worm gear 54 will resist anexternal force applied to the drive arm 16 in a direction away from thecab entry position and towards the stowed position as a result of theengagement.

The running board 12 remains in the cab entry position until the door 86of the motor vehicle 28 is returned to the closed position. When thedoor 86 is pivoted inwardly from the open position to the closedposition, the switch member 84 associated therewith is activated andsends a signal to the electronic control unit 24. The electronic controlunit 24 in response to the signal supplies an appropriate voltage to themotor assembly 22 which will pivot the drive arm 16 to move the runningboard 12 to the stowed position. Specifically, the shaft of the motorassembly 22 rotates the lead worm 55 causing rotation of the worm gear54 in a second rotational direction which in turn rotates the ball screwmember 52. The actuator shaft tube 58 is rotatable with the ball screwmember 52 and causes the drive arm 16 to pivot inwardly towards themotor vehicle 28 to move the running board 12 to the stowed position.

It is appreciated that in one embodiment at least two stops are locatedon each drive arm 16 and idler arm 18 to abut the running board 12. Thedrive arm 16 includes a stow stop 82 and end stop 80 formed at alocation between the joint 75 and second end 70. The running board 12abuts the stow stop 82 to stop further movement of the running board 12when the board 12 has reached the stowed position. The running boardabuts the end stop 80 when the board 12 has reached the box side stepposition to stop further movement of the running board 12. In oneembodiment, the stow and end stops 82, 80 include bumpers 81 formed fromurethane or a other suitable material. The stow stop 82 and electroniccontrol unit 24 are used to turn off the motor 78 of the motor assembly22. The running board 12 will continue to move towards the stowedposition until the running board abuts the stow stop 82. A current spikeis generated in the motor assembly 22 as a result of the motor assembly22 meeting a resistance to movement when the running board 12 hits thestow stop 82. The current spike will be instantaneously detected by theelectronic control unit 24. In response to the current spike, theelectronic control unit 24 turns off the motor 78. Likewise, the runningboard 12 will continue to move towards the box side step position untilthe running board abuts the end stop 80. A current spike is generated inthe motor assembly 22 as a result of the motor assembly 22 meeting aresistance to movement when the running board 12 hits the end stop 80.The current spike will be instantaneously detected by the electroniccontrol unit 24. In response to the current spike, the electroniccontrol unit 24 turns off the motor 78.

Referring to FIG. 8, the motor vehicle 28 may include an input membersuch as a body-mounted switch 96, an end cap switch 98, or a key fob toinitiate movement of the running board 12 into and out of the box sidestep position. The body-mounted switch 96 and the end cap switch 98 maybe electrically connected to the electronic control unit 24 by wiremembers 100 or by a wireless connection. The body-mounted switch 96 iseasily accessible by hand and the end cap switch 98 may be accessed by auser's foot. Thus, the running board 12 may be hand-operated, orfoot-operated if hands-free operation of the running board 12 isdesired. The running board 12 may be moved into the box side stepposition from either the stowed position or the cab entry position. Uponactivation of one of the switches 96, 98 or the key fob, a signal issent to the electronic control unit 24. The electronic control unit 24in response to the signal supplies an appropriate voltage to the motorassembly 22 to cause rotational movement in a first direction which willconvert rotary input to linear motion and pivot the drive arm 16linkages to move the running board 12 to the box side step position.

To move the running board 12 out of the box side step position and intothe stowed position, the body-mounted switch 96, the end cap switch 98,or the key fob is activated which sends a signal to the electroniccontrol unit 24. The electronic control unit 24 in response to thesignal supplies an appropriate voltage to the motor assembly 22 to causerotational movement in a second rotational direction which will convertrotary input to linear motion and pivot the drive arm 16 linkages tomove the running board 12 to the to the stowed position. Specifically,the motor shaft of the motor assembly 22 rotates the lead worm 55causing rotation of the worm gear 54 in a second rotational directionwhich in turn rotates the ball screw member 52. The actuator shaft tube58 rotates with the ball screw member 52 and causes the drive arm 16 topivot inwardly towards the motor vehicle 28 to move the running board 12to the stowed position. The running board 12 reaches the stowed positionwhen the running board 12 abuts the stow stop 82 on the drive arm 16. Acurrent spike is generated in the motor assembly 22 as a result of themotor assembly 22 meeting a resistance to movement when the runningboard 12 hits the stow stop 82. The current spike will beinstantaneously detected by the electronic control unit 24. In responseto the current spike, the electronic control unit 24 turns off the motor78. It is further contemplated that in the alternative the running board12 may be moved from the box side step position to the cab entryposition. It is appreciated that in one embodiment the stops for linearactuation are internal without any external stops.

The description of the invention is merely exemplary in nature and,thus, variations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A running board assembly for a motor vehicle, said running boardassembly comprising: a housing assembly; a linear actuator assemblypartly disposed within said housing assembly; a running board operablycoupled to said linear actuator assembly and movable relative to saidhousing assembly between at least a stowed position and deployedposition; and a motor operably coupled to said linear actuator assemblyfor driving said linear actuator assembly in opposing first and seconddirections to move said running board horizontally between at least saidstowed position and deployed position.
 2. The running board assemblyaccording to claim 1, further comprising a drive arm operably coupled tosaid linear actuator assembly and fixedly secured to said running boardfor pivotally moving said running board between said at least stowed anddeployed positions.
 3. The running board assembly according to claim 2,wherein said linear actuator assembly includes a rotatable ball screwmember operably coupled to said motor, and wherein rotation of said ballscrew member drives pivotal movement of said drive arm.
 4. The runningboard assembly according to claim 3, wherein said drive arm includes afirst link pivotably connected to a second link at a joint, whereinrotation of said ball screw member drives relative movement of saidfirst link and second link for pivotally moving said running boardbetween said at least stowed and deployed positions.
 5. The runningboard assembly according to claim 3, wherein said housing assemblyincludes a tube portion and said ball screw member is disposed withinsaid tube portion.
 6. The running board assembly according to claim 5,wherein said linear actuator assembly includes a worm member and selflocking member operably coupled toward one end of said ball screw memberand disposed within said housing assembly.
 7. The running board assemblyaccording to claim 6, wherein said linear actuator assembly includes aball nut operably connected to said ball screw member with internal ballreturn.
 8. The running board assembly according to claim 7, wherein saidlinear actuator assembly further comprises an actuator shaft tubeoperably coupled to said ball screw member, and, at a second end to aspherical bearing, said spherical bearing pivotably connected to saidfirst link of said drive arm.
 9. The running board assembly according toclaim 2, wherein said drive arm includes a stow stop engageable withsaid running board to stop said running board in said stowed positionand an end stop engageable with said running board to stop said runningboard in said deployed position.
 10. The running board assemblyaccording to claim 1, including an electronic control unit operablycoupled to said motor and electronically controlling operation thereof.11. The running board assembly according to claim 10, wherein saidelectronic control unit is programmed to turn off said motor after apredetermined number of armature revolutions to stop said running boardin said cab entry position.
 12. A running board assembly for a motorvehicle, said running board assembly comprising: a housing assembly witha linear actuator assembly; a running board operably coupled to saidlinear actuator assembly and movable relative to said housing assemblybetween a plurality of positions; a drive arm fixedly secured to saidrunning board and operably coupled to said linear actuator assembly,said drive arm including a first stop engageable with said running boardto stop said running board in one of said plurality of positions and asecond stop engageable with said running board to stop said runningboard in another of said plurality of positions; a motor operablycoupled to said linear actuator assembly for driving said drive arm topivotally move said running board horizontally between said a pluralityof positions; and an electronic control unit operably coupled to saidmotor and programmed to turn off said motor after a predetermined numberof armature revolutions to stop said running board in said cab entryposition.
 13. The running board assembly according to claim 12, furthercomprising a switch member transmitting a signal to said electroniccontrol unit to move said running board between said a plurality ofpositions upon the opening and closing of a motor vehicle door.
 14. Therunning board assembly according to claim 12, further comprising aswitch member electronically connected to said electronic control unitand providing a signal thereto for moving said running board into andout of at least one of said a plurality of positions.
 15. A runningboard assembly for a motor vehicle, said running board assemblycomprising: a mounting bracket adapted for attachment to the motorvehicle; a running board movable relative to said mounting bracketbetween a stowed position tucked underneath the motor vehicle and atleast one deployed position, to provide a user with access to the motorvehicle; a motor operably coupled to said running board for drivinghorizontal movement thereof; an electronic control unit electronicallyconnected to said motor, said electronic control unit selectivelyprogrammable to turn off said motor to stop said running board in saidcab entry position; and a housing assembly with a linear actuatorassembly partly disposed therein and including a rotatable worm memberand a lead worm that is self locking operably coupled to said motor,said housing assembly including a steel tube portion for receiving arotatable ball screw member of said linear actuator assembly that isoperably coupled to said worm member, said linear actuator assemblycoupled to said motor for driving said linear actuator assembly inopposing first and second directions to move said running board betweensaid stowed position and said at least one deployed position.
 16. Therunning board assembly according to claim 15, further comprising aswitch member electronically connected to said electronic control unitand providing a signal thereto for moving said running board into andout of at least one of said positions.
 17. The running board assemblyaccording to claim 15, further comprising a drive arm operably coupledto said linear actuator assembly and fixedly secured to said runningboard for pivotally moving said running board between said stowed and atleast one deployed, positions.
 18. The running board assembly accordingto claim 17, wherein said drive arm includes a first link pivotablyconnected to said linear actuator and pivotably connected to a secondlink at a joint, said second link pivotably connected to said runningboard, wherein rotation of said ball screw member drives relativemovement of said first link and second link for pivotally moving saidrunning board between said stowed and at least one deployed, positions.19. The running board assembly according to claim 18, wherein said jointis pivotably connected to a hub structure pivotally securing said drivearm to said mounting bracket.
 20. The running board assembly accordingto claim 17, wherein said drive arm includes a first stop engageablewith said running board to stop said running board in said stowedposition and a second stop engageable with said running board to stopsaid running board in said deployed position.